1. Field of the Invention
The present invention relates to a laser treatment tool for, for example, performing a laser treatment, a laser transmission path insertable into the laser treatment tool, and an external tube for forming the laser transmission path.
2. Description of the Prior Art
Conventionally, a treatment method using an endoscope is used as a treatment method capable of providing a treatment with little burden on a patient. According to such a treatment using an endoscope, an endoscope tube is inserted into the body from the oral cavity or the like, and imaging or a surgical operation is performed by use of a tip structure section of the endoscope tube.
Imaging is performed as follows. Illumination light is provided from the tip structure section, and the illumination light reflected by a body tissue is received by a lens provided in the tip structure section and transmitted from the endoscope tube to an endoscope main body device. The endoscope main body device puts the light into an image and displays the image on a display device. Alternatively, imaging is performed as follows. An image is shot by an imaging element such as a CCD sensor or the like provided in the tip structure section of the endoscope tube, and an image signal formed by the tip structure section is transmitted via the endoscope tube to the endoscope main body device. Then, an image is displayed on the display device.
A surgical operation is performed by a tip of appropriate forceps which are inserted from a forceps insertion opening called a “channel” and coming out from a forceps exit in the tip structure section. As the forceps, any of various tools including holding forceps, a knife and the like can be usable.
As a tool insertable from the forceps insertion opening and usable for a surgical operation, a tool using a laser transmission path for providing laser light for treatment (herein after, referred to as the “treatment laser light”) has been proposed (see Patent Document 1). The laser transmission path in Patent Document 1 is described as guiding gas such as carbon dioxide or the like, together with CO2 laser light, through a hollow tube-like waveguide path (herein after, referred to as the “hollow waveguide path”).
The gas guided through the hollow waveguide path is described as acting as a cooling fluid for cooling the hollow waveguide path which has been heated by the laser light.
As a structure of a laser transmission device which uses a carbon dioxide laser and is usable for a processing device, a structure including a water passage in an outer part thereof for cooling the hollow waveguide path for transmitting carbon dioxide laser light has been proposed (see Patent Document 2).
In a cauterization operation performed by use of a laser for treatment, especially in endoscopic submucosal dissection (ESD) or endoscopic mucosal resection (EMR), it is required to eject assist gas or physiological saline solution in order to securely obtain a visual field by expanding an operation target space and by removing transpired substances or fumes, or to recover cooling water which has been used to cool the hollow waveguide path. However, there has not been a structure for realizing both of the ejection of the assist gas or the physiological saline solution and the recovery of the cooling water with one laser transmission path.